Fatty alcohols denote an important category of industrial biochemical. For example, worldwide annual sales of fatty alcohols and their derivatives are in excess of US$1 billion. These molecules and their derivatives have numerous applications, including use as surfactants, lubricants, plasticizers, solvents, emulsifiers, emollients, thickeners, flavors, fragrances, and fuels. Due to their amphiphilic nature, fatty alcohols behave as nonionic surfactants, which are useful in personal care and household products, for example, detergents. The shorter chain fatty alcohols are used in the cosmetic and food industries as emulsifiers, emollients, and thickeners.
In nature, fatty alcohols are made by enzymes that are able to reduce various acyl-ACP or acyl-CoA molecules to the corresponding primary alcohols (e.g., U.S. Pat. Nos. 8,323,924; 8,268,599 and 8,097,439; and U.S. Patent Publication Nos. 20120282663 and 20100105963, incorporated by reference herein). However, current technologies involve mostly inorganic catalyst-mediated reduction of fatty acids to the corresponding primary alcohols. These fatty alcohols are produced via catalytic hydrogenation of fatty acids produced from natural sources, such as coconut oil, palm oil, palm kernel oil, tallow and lard, or by chemical hydration of alpha-olefins produced from petrochemical feedstocks. Fatty alcohols derived from natural sources have varying chain lengths, which are relevant and specific to particular applications. Dehydration of fatty alcohols to alpha-olefins can be accomplished by chemical catalysis.
Fatty aldehydes can be used to produce industrial specialty chemicals. For example, aldehydes are commonly used to produce polymers, resins, dyes, flavorings, plasticizers, perfumes, and pharmaceuticals. Aldehydes can also be used as solvents, preservatives, and disinfectants. Certain natural and synthetic compounds, such as vitamins and hormones, are aldehydes, and many sugars contain aldehyde groups. Fatty aldehydes can be converted to fatty alcohols by chemical or enzymatic reduction.
A greener and cleaner alternative to the production of fatty aldehydes and fatty alcohols is via fermentable sugars and/or biomass. However, in order for the production of fatty aldehydes and fatty alcohols from fermentable sugars or biomass to be commercially viable, industrial processes must be optimized for efficient conversion and recovery of the final product. The present disclosure addresses this need by providing compositions and methods for improved production of fatty aldehydes and fatty alcohols by using engineered host cells as biocatalysts.